How many characters is one SMS?

160 characters when the message uses only the GSM-7 alphabet, because a single SMS carries 140 bytes at seven bits per character. If the message contains any character outside GSM-7 it switches to UCS-2 (Unicode) at sixteen bits per character and the limit drops to 70 characters.

Why is my SMS counted as multiple messages?

Messages longer than one segment are split into parts, and each part carries a six-byte header. That reduces the payload to 153 characters per part in GSM-7 and 67 per part in UCS-2, so a 161-character message bills as two segments and a 307-character message as three.

Do emojis reduce the SMS character limit?

Yes. A single emoji forces the whole message into UCS-2 encoding, cutting the single-segment limit from 160 characters to 70. Most emoji also occupy two units rather than one. Curly quotes, en and em dashes, the ellipsis character and non-breaking spaces have the same effect.

SMS Character Counter

Q: Which characters count as two in an SMS?

In GSM-7 the extension-table characters each count as two: the caret, curly braces, square brackets, tilde, backslash, pipe and the euro sign. They do not force Unicode encoding, but they do consume two of your 160 characters each.

Paste or type a message to see how many characters it uses, which encoding it triggers, and how many segments your carrier will bill you for. Nothing is sent anywhere — it all runs in your browser.

Why an SMS is 160 characters — and when it isn't

A single SMS carries 140 bytes. Using the GSM-7 alphabet, seven bits per character, that is 160 characters. The moment your message contains one character outside that alphabet, the whole message switches to UCS-2 (Unicode) at sixteen bits per character, and the limit drops to 70 characters. One emoji, one curly quote pasted from Word, one em dash, and a 150-character message becomes three segments instead of one.

How multi-part messages are counted

Longer messages are split and reassembled on the handset, but each part carries a six-byte header that eats into the payload. So concatenated messages are not 160 characters each — they are 153 characters per part in GSM-7 and 67 per part in UCS-2. This is why a 161-character message costs two segments and a 320-character message costs three.

Characters that quietly cost you double

These are the usual culprits behind an unexpected encoding switch: curly quotes and apostrophes, the en and em dash, the ellipsis character, non-breaking spaces, accented letters outside the GSM set, and every emoji. Straight quotes, hyphens and three full stops are all GSM-safe substitutes.

There is also a small set of GSM characters that count as two rather than one, because they live in an extension table: the caret, curly and square brackets, tilde, backslash, pipe and the euro sign. A message full of square brackets costs more than it looks.

Why segment count matters

You are billed per segment, not per message, by every US provider — so a three-segment message costs three times a one-segment message to the same recipient. Carrier pass-through fees are also charged per segment. Trimming a marketing message from 168 to 155 characters halves its cost, and on a 100,000-recipient send that is a real number. See our SMS pricing for per-segment rates, or the breakdown of what US SMS actually costs across providers.

Writing to fit

Keep transactional messages inside one GSM-7 segment where you can.
Include your brand name — carriers expect it and recipients need it — and count it in your budget.
Opt-out language costs characters too. "Reply STOP to opt out" is 22 of your 160.
Use your own short URLs rather than public link shorteners, which are filtered.
Paste drafts through a plain-text editor first to strip smart quotes.

Sending at volume and want the segment maths done on your real traffic? Talk to the Signalmash team — we will look at a month of your messages and tell you what encoding and segmentation are costing you.